Multiple sclerosis (MS) is the most common chronic inflammatory disease of the central nervous system1, whose demyelination is the pathological hallmark. MS is characterized by neuroinflammation, demyelination, axonal damage, and neurodegeneration2. The demyelination state in brain and the clinical course are difficult to predict in the early stage of disease. Recently, several neuroimaging and fluid biomarkers had been explored in MS. Using brain amyloid positron emission tomography (PET) in active MS had showed that both the damage sites and normal appearance white matter had a lower intensity than non-active MS. The result suggests a predictive role that the intensity from amyloid PET could reflect the disease activity and link to early myelin damage. The levels of tau protein in cerebrospinal fluid (CSF) had also been showed a negative correlation with brain atrophy, which is a prognostic marker for MS. In fluid biomarkers, both neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) had been used in MS and reported correlations with disease severity, the extent of neuroinflammation and progression. In current study, investigator will enroll 38 participants with MS and evaluate their clinical severity; measure the WM lesion and disease activity by magnetic resonance imaging (MRI); myelination state and amyloid deposition by amyloid PET scan; tau deposition by state of-art tau PET scan. Investigator also measure the serum levels of NfL and GFAP as the index of axonal injury and disease activity. The relationship between disease severity, brain myelination, tau deposition and serum levels of NfL will be discuss.

Inclusion Criteria:

1. Age between 20-75 years old
2. Multiple Sclerosis patients

Exclusion Criteria:

1. Implantation of metal devices including cardiac pacemaker, intravascular metal devices.
2. Major systemic diseases including coronary arterial disease, heart failure, uremia, hepatic failure, prominent strokes, acute myocardial infarction, poorly controlled diabetes, previous severe head injury, intracranial operation, hypoxia, sepsis or severe infectious diseases.
3. Major psychiatric disorders, drug or alcohol abuse and major depression
4. Pregnant women or breast- feeding women.
5. Patients in whom MRI was contraindicated or patient had claustrophobia.
6. History of severe allergic or anaphylactic reactions particularly to the tested drugs.
7. History of positive test for human immunodeficiency virus (HIV).
8. Indication of impaired liver function as shown by an abnormal liver function profile at screening (eg. repeated values of aspartate aminotransferase [AST] and alanine aminotransferase [ALT] ≧ 3X the upper limit of normal values).